You would think that nothing could fazePaul McCartneyat this point in his life. After all, the 82-year-old music icon was in the Beatles, one of the most popular bands of all time, and then went on to have an incredibly successful career with Wings and as a solo artist. Yet, McCartney revealed in a new interview posted on his own website that it was "nerve-wracking" and "nail-biting," and he was "pretty terrified" working withBarbra Streisand, 83, on a duet of his song "My Valentine." It's featured on Streisand's forthcoming album,The Secret Life: Partners: Volume 2, due June 27. The single andlyric videoof the duet is out now. 🎬SIGN UP for Parade's Daily newsletter to get the latest pop culture news & celebrity interviews delivered right to your inbox🎬 McCartney's original version of the song appeared on his 2012 albumKisses on the Bottom. "I think the session was about three hours, you know, a normal kind of session, and it was produced by my friendPeter Asher. But it started off with a big 40-piece orchestra on the Sony lot, which is one of the old Hollywood film studios; it's very impressive. And we were on 'The Barbra Streisand Scoring Stage', so no pressure there!" he recalled. "I thought, 'Well, this will be easy because it's my song, it's "My Valentine." What can go wrong?' But what I'd forgotten was that they'd arranged it so that it had to go in Barbra's key and then in my key. So, to get from Barbra's key into mine was kind of difficult, and I had to launch in not knowing what key I was in. Mine was lower, hers was higher. It wasn't easy at all!" Related: Barbra Streisand Teases 'My Valentine' Duet With Paul McCartney Michael Bubléalso released a version of the song in 2022, which was produced by McCartney, and he said he was happy to have Streisand record the song. "I thought if Barbra is going to do my song, I've got to encourage that," McCartney added. "And she was great. I didn't realize how rounded she is, creatively. They were filming the session and as soon as we went in, she said, 'Who put that camera there? That shouldn't be there, bring it over here. And what about those lights?' I thought, 'Wow, you're directing it!' But then I suddenly remembered she's directed three big movies. She's a smart cookie."